The present invention relates generally to a pressure regulator, and particularly to a pressure regulator having an improved seat and seating assembly for controlling fluid flow through the pressure regulator.
Pressure regulators are used in fluid systems to regulate the flow of fluid through the pressure regulator, and thereby to maintain a desired downstream fluid pressure. Typically, a pressure regulator is used to reduce the pressure of a fluid from a higher pressure to a lower pressure. For example, some fluid systems utilize gas stored in a cylinder as a source of gas for various needs, such as fuel for a gas welding system. However, the gas must be stored at a high pressure so that as much gas as possible can be stored within the limited volume of the cylinder. In the example of a gas welding system, the system components that receive the gas typically do not operate at the pressure of the gas in the cylinder. Therefore, a pressure regulator is typically used to reduce the pressure of the gas supplied by the cylinder down to a lower gas pressure that is more conducive for use with the welding system.
Typically, a pressure regulator has an inlet, an outlet and a valve to control the flow of fluid from the inlet to the outlet. The regulator senses the pressure downstream and opens the valve to allow additional fluid to flow through the regulator to raise the pressure downstream. The pressure regulator closes the valve once the desired downstream pressure has been achieved. A typical valve for a pressure regulator has a valve seat and a seating surface surrounding an orifice. When downstream pressure is lower than desired, the valve directs the seat away from the seating surface to allow fluid to flow through the orifice to raise the pressure of the fluid downstream. When the desired downstream pressure is achieved, the valve urges the seat against the seating surface to prevent more fluid from flowing through the orifice.
In a typical pressure regulator, several forces act on the seat. A biasing spring is typically used to maintain the seat against the seating surface when no other forces are acting on the seat, or when the sum of the other forces acting on the seat is zero. A regulating spring is typically used to establish the desired downstream pressure. The force of the regulating spring is coupled to the seat through a diaphragm. The diaphragm is flexible and couples the pressure of the fluid downstream of the seat to the regulating spring. When the force produced by the pressure of the fluid acting on the diaphragm is greater than the force applied by the regulating spring, the diaphragm is positioned so that the seat is seated against the seating surface. When the force produced by the pressure of the fluid acting on the diaphragm is less than the force applied by the regulating spring, the diaphragm is positioned so that the seat is unseated from the seating surface, allowing fluid to flow downstream and raising the pressure downstream. Eventually, the rise in pressure downstream will be sufficient to overcome the regulating spring force and close the seat, thereby establishing the downstream pressure. By varying the force applied to the diaphragm by the regulating spring, the downstream pressure can be adjusted. A threaded mechanism is typically used to vary the force applied by the spring on the diaphragm by compressing or uncompressing the regulating spring.
In operation, the seat may be seated and unseated rapidly and with great frequency. The repeated seating and unseating of the seat may damage the seat and even produce an audible humming sound. Consequently, devices are commonly used to dampen the movement of the seat. These devices are typically placed between the seat and a fixed surface to produce friction. However, these dampening devices add to the complexity of assembling and operating the pressure regulator.
Additionally, the seat is typically ring-shaped and composed of a material, such as rubber or tetraflourethylene, which has poor memory characteristics. These materials are plastically deformed when seated against the seating surface. While this enables a good seal to be made between the seat and the seating surface, because of the plastic deformation, the seats do not return to their original shape when unseated. Particles can collect in these seats and are retained in the material due to the plastic deformation of the materials. These particles reduce the ability of the seat to form a seal.
The typical valve stem extends through the center of the ring-shaped seat. The typical valve stem also has a conical portion that serves to support and guide the seat, and that serves as part of the seat for sealing purposes. Consequently, the valve stem is usually composed of a metal that must be electro-polished, adding significant expense to the cost of the valve stem.
There exists a need for a pressure regulator valve assembly that solves some or all of the problems outlined above. Specifically, there is a need for a seat that is operable to dampen its own movement without the need for extra parts, such as friction dampers. Additionally, there is a need for a seat that is elastically deformed when seated, rather than plastically deformed. Furthermore, there is a need for a pressure regulator that does not require metal components, such as valve stems, to be electro-polished.
The present technique provides a novel regulator designed to respond to such needs. According to one aspect of the present technique, a pressure regulator comprises a seat and a seat retainer. The seat and seat retainer control fluid flow through the pressure regulator. The seat retainer has a hollow interior with an interior surface. The seat is movable and is disposed within the hollow interior of the seat retainer. The seat is adapted such that it slidingly engages the interior surface of the seat retainer during movement of the seat. The sliding engagement dampens the movement of the seat.
According to another aspect of the present technique, a pressure regulator is provided that comprises a seat and a seating surface. The seat is seated against the seating surface to prevent fluid from flowing through the pressure regulator. The seat is elastically deformed by the seating surface when it is seated against the seating surface.
According to yet another aspect of the technique, a pressure regulator is featured that comprises a seat, a seat retainer, a diaphragm, and a stem. The seat retainer has an orifice that enables fluid to flow through the seat retainer. The seat has a solid body and is disposed within the seat retainer. Additionally, the seat is movable relative to the seat retainer. In a first position of the seat, the seat is disposed against the seating surface so that fluid flow through the orifice is blocked. In a second position of the seat, there is a path for fluid to flow through the orifice. Furthermore, the stem extends through the orifice and is affixed to the seat. The stem is operable to move the seat in response to movement of the diaphragm.